This proposal builds upon made from our original NCVDG awarded to the University of Washington in 1987. This NCVDG was composed of collaborative groups from the Regional Primate Research Center (RPRC), the Departments of Immunology, Laboratory Medicine, Medicine, Microbiology and from the Bristol-Myers Squibb Pharmaceutical Research Institute (then Oncogene) in Seattle. In this application, the key individuals of the first NCVDG propose to continue and expand their collaboration to extend the development of recombinant subunit vaccines that will elicit a broad range of cellular and humoral immune responses for the immunoprophylaxis of simian and human immunodeficiency viruses (SIV and HIV-1). We plan to assess the protective efficacy of these vaccines as sole immunogens and in combination regimens in the SIV and HIV-1 nonhuman primate models against experimental challenge from cell- free and cell-associated viruses administered intravenously, intrarectally and intravaginally. More specifically, Project 1 involves the development and the characterization of candidate recombinant vaccines. Vaccinia virus recombinants will be constructed that express the env, the gag and pol, or the combination of the three viral proteins (pseudovirions) from two SIV isolates (SIV mne and SIV smm/H-4 and two HIV-1 isolates (IIIB and MN). Immune response generated by the subunit vaccines, alone or in combination with recombinant virus priming, will be compared to that generated by attenuated live virus vaccines. Adeno- associated virus will be studied as an alternative to vaccinia virus from priming. Several adjuvant formulations for subunit antigen boosting will also be evaluated. In Project 2, cellular immune responses, including lymphoproliferative responses to mitogens, soluble antigens, vaccinia, SIV and HIV-1 antigens will be assayed. In particular, T cell cytotoxicity to SIV and HIV-1 will be examined. The role of T-cell mediated immunity will be studied by adoptive transfer experiments. In Project 3, the immunogenicity, tolerance and protection rate of these vaccine regimens will be tested in the Macaca fascicularis or the Macaca nemestrina modes. Detailed evaluation of the host response will be performed, including antibody response to SIV and HIV-1 polypeptides, neutralizing antibodies to homologous and heterologous viruses and ADCC activities. Challenge studies to evaluate the efficacy of each of these candidate vaccine in preventing infection, viremia and subsequent immunodeficiency disease will be performed. The virological (Project 1) and immunological (Project 2) properties of breakthrough viruses in vaccine failures will be analyzed. Studies of the immune responses, the protective efficacies and the breakthrough viruses will provide critical information about the correlates of protective immunity and further insight into future clinical trails of candidate vaccines.